Dorothea Lange’s name is nearly synonymous with the Great Depression, which gave rise to her famously unflinching portrayals of human suffering. But in 1933, she was making her living as a portrait photographer, shooting the social elite in her San Francisco studio. The Depression had begun to take a toll on her business, however, and one idle day as she gazed out her window, Lange was struck by the number of unemployed and homeless men waiting in breadlines and idling on the sidewalks. She decided to go into the streets and photograph what she saw.

Near her apartment was the White Angel soup kitchen, where a crowd of men in hats and worn overcoats had lined up for food. Lange was nervous about photographing the men, worried that she might offend someone or move too slowly and miss a good shot. One of the pictures she took that day, White Angel Breadline, a haunting portrait of a haggard man with a tin cup, cemented her reputation when it was published by U.S. Camera in 1935. “I can only say I knew I was looking at something,” recalled Lange to an interviewer some 30 years later, according to Linda Gordon in Dorothea Lange: A Life Beyond Limits, 2009. “Sometimes you have an inner sense that you have encompassed the thing.”

And the picture’s importance has endured: In October 2005, a print of White Angel Breadline that Lange signed and gifted to Chicago’s Museum of Science and Industry in 1936 was auctioned at Sotheby’s for $822,400 (est. $200–300,000), making it the most expensive Lange photograph ever sold. The price reflects not only the significance of the particular image and the centrality of Lange’s Depression-era photographs to her oeuvre, but also the scarcity of her vintage prints—those made no more than a couple of years after a photograph is taken.

“I think the market has come to the realization that her prints are much rarer than once thought,” says New York photography dealer Bruce Silverstein, who has frequently handled sales of her work. He notes that Lange’s death in 1965 preceded both “the print revolution of the 1970s when many of the early artists were going back and reprinting from their negatives” as well as an established market for fine art photography.

As a result, the gap in price between vintage Langes, printed shortly after she shot them, and those she made later, is one of the widest seen anywhere in the photography market. Experts suggest vintage prints of White Angel Breadline will bring anywhere between $300,000 and $800,000, depending on condition and provenance. Prices for later prints, though lower, tend to stay in the five-figure range, according to auction databases. In the same year that Sotheby’s sold the record-setting print, Christie’s sold a White Angel Breadline printed in the 1950s for a hammer price of $32,000 (est. $30–40,000). In short, says Silverstein, collectors and institutions that cannot pay a hefty premium “are willing to accept the fact that a print might not be made at the time of the negative but a little bit later. As long as it was done within her lifetime there seems to be more interest for that work.”

A similar stratification is seen in the prices realized?for Lange’s most famous image, Migrant Mother, her ?haunting 1936 photograph of a destitute California? farmworker surrounded by her children. In today’s?market, most examples for sale are later prints, made ?in the 1950s or ’60s. Christie’s sold one for $35,000 ?(est. $10,000–15,000) this past spring, and San Francisco ?dealer Scott Nichols had one in his recent exhibition “Dorothea Lange: A Photographer’s Journey” that was printed in the 1950s and whose price he expected to be “somewhere around $75,000.” On October 30, Bonhams will offer a print of Migrant Mother in its photography sale that was “probably printed mid-1950s,” according to the catalogue description, and carries an estimate of $30,000 to $50,000.

In contrast, “the last significant print of Migrant Mother to come up was in 1998,” says Denise Bethel, head of the photographs department at Sotheby’s, “and we got a quarter-million dollars for that.” The photo—which Bethel describes as “unbelievable,” an extremely high-quality early print with handwritten notes and Lange’s signature—was snagged by the deep-pocketed Getty Museum. “If one were to come up now,” says Bethel, “if it were the right print, it could easily bring half a million dollars, maybe a million dollars.”

Art adviser Amanda Doenitz, however, cautions collectors to be especially careful when looking to purchase any of Lange’s most in-demand images. In the past 10 years, what she calls “dubious Langes” have appeared on the market, with shaky provenances and loose dating. “The best advice that I could give is to not take anything at face value,” she says. Potential buyers must pay attention to print quality; photo paper; various stamps from her employer, the Farm Security Administration (which stamped all of its prints); and whether Lange signed or wrote on the back. “Everybody knows Lange’s hand,” Doenitz says.

Lange was born Dorothea Nutzhornin Hoboken, New Jersey, in 1895. When she was seven she contracted polio, which left her with a limp, and her parents separated five years later, after which her mother moved the family to New York City. After her high school graduation, Lange declared that she wanted to be a photographer, despite the fact that she had never held a camera.

In the face of her mother’s disapproval, Lange made her own way, landing a job in 1912 or 1913 in the shop of famed photographer Arnold Genthe, who gave Lange both her first training and her first camera. She went on to apprentice herself to seven other photographers and took a course with Clarence H. White at Columbia University’s Teachers College.

But it wasn’t until Lange arrived in San Francisco, in 1918, that she became a photographer in her own right. She set up a portrait studio the following year and found almost immediate success. Also around this time, she formally adopted her mother’s family name and met the painter Maynard Dixon. The two married in 1920. Throughout the 1920s, Lange occasionally experimented with subject matter, but she remained focused on studio work, establishing a geographically widespread clientele and drawing accolades from the San Francisco Chronicle.

After the experience of capturing White Angel Breadline, Lange began to undergo a political transformation. She went out into the streets more, photographing signs of unemployment and strikes, and the resulting pictures were shown at her first solo exhibition, in 1934, at filmmaker Willard Van Dyke’s 683 Brockhurst Gallery.

Today, strong examples from this early period are drawing increasing interest: The General Strike, Policeman, San Francisco, 1934, sold for $43,750 (est. $35–$45,000) at Phillips de Pury & Company in October 2010, and The Human Face, 1933, went for $40,000 at Christie’s (est. $5,000–$7,000) the following year. “I feel like people are connecting most with the works that are documenting the face of the issues,” says Vanessa Kramer, worldwide director of photographs at Phillips. “The portraits—as long as the print is of good quality—those are the ones that are consistently selling best.”

This was, in fact, the core of Lange’s breakthrough in documentary photography: She made portraits of the impoverished using the same techniques she had developed as a studio photographer for the wealthy. This combination reached its apex in Migrant Mother. Lange made the now iconic picture two years after meeting the economist and social activist Paul Taylor, for whom she undertook fieldwork to supplement a massive study of the living conditions of California’s farmworkers. The two fell in love and divorced their spouses so they could marry. Ultimately, Taylor’s report earned only a small amount of money from the FSA to build workers’ camps, but the Resettlement Administration, as the FSA was formerly known, offered Lange a job as part of its effort to create a public photographic record of rural life in America.

It was in this position that she created a vast trove of? work, much of which was dispersed to various government? archives and is now housed at the Library of Congress.? Of an estimated 41,000 FSA photos in the collection of ?the New York Public Library, 3,090 are images by Lange. ?These images were again in the news this past summer? when the library put another 1,014 FSA images online, including 159 by Lange, that are not in the Library of Congress’s online catalogue. “Although these are quite rare, we cannot be certain that all of them are unique to this collection,” says Stephen Pinson, assistant director of arts, prints, and photographs and the Robert B. Menschel curator of photography at the library.

Lange was laid off from the FSA in 1940, but she continued to work on projects for various government agencies for the next five years. The decade from 1935 to 1945 is considered the peak of her career. But because collectors have historically focused on a relatively small fraction of her output, lesser known works from this period can still be had at affordable prices.

FSA pictures tend to be more desirable, starting in the $12,000-to-$15,000 range and escalating “very quickly” on the basis of condition and provenance, according to Nichols. Other photographs taken around that time but printed in the 1950s or ’60s may be priced as low as $5,000.

Lange’s health began to deteriorate in 1945; she spent the next 20 years battling chronic ulcers and, in her last year, esophageal cancer. However, she continued to work throughout her life, shooting projects and submitting them to Life in the 1950s. Two of those projects—a series of portraits of the inhabitants of County Clare, Ireland, and a visual profile of an Oakland public defender—have seen growing interest of late, with some of the more recognizable images bringing 134 $20,000 to $25,000. Others go for $4,000 to $9,000.

Lange’s reputation was set in 1966, a year after her death, when her work was given a solo exhibition at New York’s Museum of Modern Art. “In terms of classic photography, Lange is probably the most expensive female photographer in the world,” says Bethel.

Yet galleries are just beginning to market her broader oeuvre. “In the early days of the market, in the 1970s, there was more interest in Lange’s work for historical reasons,” says Deborah Bell, head of photographs at Christie’s. “Now people know some of the major pictures from each artist’s career, and so the market is more image-driven than it used to be.”

Hannah Sloan, director of special projects at the Rose Gallery, in Santa Monica, echoes Bell, saying, “Until now, the most sought-after images by Lange have been the iconic ones from the Depression era.” The Rose Gallery works closely with Lange’s heirs, including her son John Dixon, who is now in his early 80s, and his wife, Lolita, in documenting and assessing prints and placing them in important private and institutional photography collections. Gallery founder Rose Shoshana is also working on a publication, in collaboration with the family, that will feature photographs made in the last years of Lange’s life, many of which have never been published.

Lange’s work for the U.S. government also involved documenting the experience of detainees in Japanese internment camps in the early 1940s. Approximately 800 of these images were impounded by the government and unearthed later in the National Archives. These and other World War II photos “have also been of great interest and are priced higher than other work by the artist,” notes Sloan. According to Gordon, Lange herself didn’t see the pictures for 20 years.

Sloan says Lange’s “more personal pictures” have ?received “less critical attention and widespread expo-sure and do not therefore command the same prices?as the iconic pictures.” However, recent auctions and ?private sales indicate that buyers are starting to take? notice of other bodies of work Lange produced. This? past spring, Lange’s photograph of her first husband,? Dixon, from 1930, sold at Sotheby’s for $8,750 (est. $7,000–10,000). At a Christie’s sale in October 2011,? her 1954 black-and-white picture of a young girl in County Clare, printed circa 1965, sold for $20,000, well above the $5,000-to-$7,000 estimate.

This past summer’s show at Scott Nichols Gallery featured a wide range of work for sale spanning the photographer’s entire career, from the lesser-known—early portraits and late pictures taken on a trip to Egypt in 1963—to the icons. Nichols characterizes many of the pieces as “moderately priced” and says that he has sold six at the time of this writing. As a result of the exhibition, he says, “we’ve started to discover more material. We just get calls. Things keep coming out.” And additional material is likely to surface as new projects reach fruition. Lange’s granddaughter Dyanna Taylor is making a documentary film about the artist titled Dorothea Lange: Grab a Hunk of Lightning, which is currently scheduled to air in late 2013 as part of PBS’s American Masters series. Taylor is also assisting Elizabeth Partridge, the author of the companion book of the same title, which will include biographical information and about 130 photos.

Still not fully tapped by scholars is a massive amount of material—Lange’s personal archive, including 25,000 negatives, 6,000 vintage prints, field notes, and memorabilia—that was given to the Oakland Museum of California by Paul Taylor following the photographer’s death. The museum holds the copyright to many of Lange’s works, including White Angel Breadline, but not to photographs that were produced as part of her work for the government—such as Migrant Mother—all of which are in the public domain. “Copyright pertains to the reproduction of the image but not to the prints themselves,” notes Sloan. “So the copyright issue has not had a noticeable effect on the sales of prints.”

Sloan says Lange’s output “was much greater than the relatively small group of pictures for which she is known. Hopefully the material that has recently come to light will contribute to Lange’s reputation as one of the 20th century’s most important photographers.”

This article originally appeared in the September 2012 issue of Art+Auction.